BREAKING CHANGE: Use ES2015 syntax

[saschanaz]

This is related to #82 but not really breaking compat with Node.js 4.

This PR converts:

• var func = function() { } style to function func() { }
• var x to let x or const x depending on the variable is reassigned or not
• ES5-style class declaration for WebIDLParseError to ES2015 one
• for (var i = 0; i < array.length; i++) to for (const item of array)
• callback functions to use arrow syntax
• object literal member functions { func: function () { } } to { func() { } }

PS: Now fixes #82 by removing it on .travis.yml.

[marcoscaceres]

Couple of nits.

[marcoscaceres]

Maybe use template literal here?

[marcoscaceres]

Maybe we should fix this now:

throw new WebIDLParseError(str, line, tok, tokens.slice(0, maxTokens))

[marcoscaceres]

nit: whitespace ?

[marcoscaceres]

Be nice if we got rid of the const x = {}, y = {}; etc. pattern usage and instead do "const x = {}; const y = {}" and so on. The "," is a pretty bad practice. We can do that in different PR tho.

[saschanaz]

nit: whitespace ?

Could you clarify more? extended_attrs already calls all_ws internally so no need to process whitespaces twice.

[marcoscaceres]

sorry, I meant changing:

const mems = [],
  ret = {};

To:

const mems = [];
const ret = {};

[marcoscaceres]

With regards to whitespace.... I literally meant that the indentation of your code is incorrect - just a nit :) The actual processing is all good 👍

[marcoscaceres]

We need to update the travis file as per #82 (i.e., drop node 4):

node_js:
  - "lts/*"
  - "6"

I don't know if this works, but we could try:

node_js:
  - "lts/*"
  - "lts/6"

[saschanaz]

We need to update the travis file as per #82 (i.e., drop node 4):

Not adding node will exclude non-LTS latest stable versions (9, 11, ...), do we want to exclude them?

[marcoscaceres]

Not adding node will exclude non-LTS latest stable versions (9, 11, ...), do we want to exclude them?

Ah, good point. Yeah, we probably want to test whatever is latest. I have to run off for a bit, can you please check travisci docs for how to do that?

[saschanaz]

https://docs.travis-ci.com/user/languages/javascript-with-nodejs/#Specifying-Node.js-versions

node latest stable Node.js release

Current node points to the latest version. Not sure whether lts/6 will work or not but it's probably not good to use an undocumented string.

[saschanaz]

lts/6 didn't work but the documentation says lts/boron works.

[marcoscaceres]

@saschanaz, sent you an invite with write access. Please merge.

I'll release after merge.

[marcoscaceres]

Please squash merge and use "BREAKING CHANGE: Use ES2015 syntax" as commit message.